1. Field of the Invention
The present invention relates to a hammering operation control unit of a piano accompanied with an automatic performance function, in which varieties of dynamic characteristics among plural keys are adjusted by controlling a drive value of each key, thereby achieving an accurate playback of musical performance.
2. Prior Art
The conventional piano accompanied with the automatic performance function (hereinafter, referred to as "automatic performance piano") is constructed such that a key actuating unit is installed in an acoustic piano (i.e., non-electronic piano), wherein this key actuating unit has plural solenoids (e.g., eighty-eight solenoids) of which number corresponds to the number of keys.
The above-mentioned key actuating unit is controlled by a controller constructed by a micro computer and the like. More specifically, by supplying certain current pattern (i.e., pulse pattern) to all of the solenoids of which number is equal to that of the keys, plungers are projected at constant velocity so that the keys are driven and strings are struck. In this case, the controller sequentially operates desirable keys in accordance with the musical tune to be performed.
However, the above-mentioned conventional automatic performance piano cannot eliminate the varieties of dynamic characteristics of the keys which are different in each piano. For example, the conventional piano cannot eliminate the variety of hammering force to be caused when the key is depressed in each piano. In addition, the conventional piano cannot eliminate the variety of dynamic characteristic which is different in each key of the same piano. For example, the conventional piano cannot eliminate such variety to be occurred when a hammering action of one key is relatively heavy and different from that of another key. In other words, the conventional key driving unit cannot compensate the dynamic characteristic of each key by controlling its drive value. Because, the conventional key driving unit simply increases or decreases currents flown through solenoid coils. As a result, there is a problem in that the conventional piano cannot set operating states of both of normally functioned keys and malfunctioned keys at the optimum states.